blender (n.)

c. 1300, blenden, "to mix in such a way as to become inextinguishable, mingle, stir up a liquid," in Middle English chiefly in northern writers, from or akin to rare Old English blandan "to mix" (Mercian blondan) or Old Norse blanda "to mix," or a combination of the two; from Proto-Germanic *blandan "to mix," which comes via a notion of "to make cloudy" from an extended Germanic form of the PIE root *bhel- (1) "to shine, flash, burn."

Compare Old Saxon and Old High German blantan, Gothic blandan, Middle High German blenden "to mix;" German Blendling "bastard, mongrel," and, outside Germanic, Lithuanian blandus "troubled, turbid, thick;" Old Church Slavonic blesti "to go astray." The figurative sense of "mingle closely" is from early 14c. Related: Blended; blending.